DEVELOPMENT OF WEARABLE BIOSENSOR - Latest Seminar · PDF fileSeminar Report ’03 Wearable Bio-Sensors 2.DEVELOPMENT OF WEARABLE BIOSENSOR 2.1.RING SENSOR It is a pulse oximetry sensor

Seminar Report ’03 Wearable Bio-Sensors

1. INTRODUCTION

Wearable sensors and systems have evolved to the point that they can be

considered ready for clinical application. The use of wearable monitoring

devices that allow continuous or intermittent monitoring of physiological

signals is critical for the advancement of both the diagnosis as well as treatment

of diseases.

Wearable systems are totally non-obtrusive devices that allow physicians

to overcome the limitations of ambulatory technology and provide a response to

the need for monitoring individuals over weeks or months. They typically rely

on wireless miniature sensors enclosed in patches or bandages or in items that

can be worn, such as ring or shirt. The data sets recorded using these systems

are then processed to detect events predictive of possible worsening of the

patient’s clinical situations or they are explored to access the impact of clinical

interventions.

Dept. of AEI MESCE Kuttippuram-1-


2. DEVELOPMENT OF WEARABLE BIOSENSOR

2.1.RING SENSOR

It is a pulse oximetry sensor that allows one to continuously monitor heart

rate and oxygen saturation in a totally unobtrusive way. The device is shaped

like a ring and thus it can be worn for long periods of time without any

discomfort to the subject. The ring sensor is equipped with a low power

transceiver that accomplishes bi-directional communication with a base station,

and to upload date at any point in time.[1]

2.1.1 BASIC PRINCIPLE OF RING SENSOR

Each time the heart muscle contracts,blood is ejected from the ventricles

and a pulse of pressure is transmitted through the circulatory system.

This pressure pulse when traveling through the vessels,causes vessel wall

displacement which is measurable at various points.inorder to detect pulsatile

blood volume changes by photoelectric method,photo conductors are

used.normally photo resistors are used, for amplification purpose photo

transistors are used.[3]

Light is emitted by LED and transmitted through the artery and the

resistance of photo resistor is determined by the amount of light reaching it.with

each contraction of heart,blood is forced to the extremities and the amount of

blood in the finger increases.it alters the optical density with the result that the

light transmission through the finger reduces and the resistance of the photo

resistor increases accordingly.The photoresistor is connected as a part of voltage

divider circuit and produces a voltage that varies with the amount of blood in the

finger.This voltage that closely follows the pressure pulse

.



2.1.2WORKING

The LEDs and PD are placed on the flanks of the finger either reflective

or transmittal type can be used. For avoiding motion disturbances quite stable

transmittal method is used. Transmittal type has a powerful LED for

transmitting light across the finger. This power consumption problem can be

solved with a light modulation technique using high-speed devices. Instead of

lighting the skiing continuously, the LED is turned ON only for a short time, say

10-100 ns, and the signal is sampled within this period, high frequency, low

duty rate modulation is used for preventing skin-burning problem.

The motion of the finger can be measure with an optical sensor. This

motion detector can be used not only for monitoring the presence of motion but

also for cencelling the noise. By using PD-B as a noise reference, a noise

cencellation filter can be built to eliminate the noise of PD-A that completes

with the noise references used. And adaptive noise cancellation method is used.

Fig.1.Noise Cancellation Mechanism

The noise-canceling filter combines two sensor signals; one is the main

signal captured by PD-A and the other is the noise reference obtained by PD-B.

The main signal mostly consists of the truce pulsate signal, but it does contain

some noise. If we know the proportion of noise contained in the main signal, we

can sensate the contained in the main signal, we can generate the noise of the


Signal Source

Main Signal

Noise Source

Noise Reference

Adaptive Filter

+-

Photo detector A

Photo detector B


same magnitude by attending the noise reference signal and then subtract the

noise from the main signal to recover the true pulsatile signal.

fig.2.prototype of ring sensor

The ring has a microcomputer performing all the device controls and low

level signal processing including LED modulation, data acquisition, filtering,

and bi-directional RF communication. The acquired waveforms sampled at

100Hz are transmitted to a cellular phone carried by the patient through an RF

link of 105Kbps at a carrier frequency of 915 MHz. The cellular phone accesses

a website for data storage and clinical diagnosis.





2.1.3. BLOCK DIAGRAM OF RING SENSOR

fig.3

Power Source

Power for light source, photo detector, RF transmitter and analog and

digital processing units provided by a tiny cell battery used for wrist watches.

Lifetime is 2 or 3 weeks.

Light Source

Light source for the ring sensor is the LED, approximately wavelength of

660 nm.



Photo Detector

Photo detector is normally photodiode or phototransistor used for

detecting the signal from the LED.

RF Transmitter

It is used for transmitting the measured signals. Its carrier frequency is

915MHz.

LED Modulation

Power consumption problem can be solved with a lighting modulation

technique. Instead of lighting the skin continually the LEDis turned on only for a

short time, say 100-1000ns and the signal is sampled within the period. High

frequency low duty cycle modulation implemented minimizes LED power

consumption.[4]

Data Acquisition

It is used to collect the data from sensor and data are sampled and

recorded.



Filtering

The signal from the PD-B as a noise reference a noise cancellation filter

can be built to eliminate the noise of PD-A that correlates with the noise

reference signal. For noise cancellation we use the adaptive noise filter.

2.1.4APPLICATIONS OF THE RING SENSOR

CATRASTOPHE DETECTION

• Wireless supervision of people during hazardous operations

Eg:military,fire fighting

• .In an overcrowded emergency department

CHRONIC MEDICAL CONDITION

• in cardiovascular desease for monitoring the hyper tension

• chronic surveillance of abnormal heart failure

2.1.5 ADVANTAGES

• continous monitoring

• detection of transient phenomena

• promote further diagnostic and therapeutic measures

• easy to use

• reducing hospitalization fee

DISADVANTAGES

• initial cost is high

• limited number of physiological parameters are to be monitored



2.2. SMART SHIRT (WEARABLE MOTHERBOARD)

Smart shirt developed at Georgia tech which represents the first attempt at

relying an unobtrusive, mobile and easy to use vital signs monitoring system;

presents the key applications of the smart shirt technology along with its impact

on the practice of medicine; and covers key opportunities to create the next

generation of truly “adaptive and responsive” medical systems.[5]

Research on the design and development of a smart shirt fort a combat

casualty care has led to the realization of the world’s first wearable motherboard

or an “intelligent” garment for the 21st century. The Georgia tech wearable

motherboard (GTWM) uses optical fibers to detect bullet wounds and special

sensors and interconnects to monitor the body vital signs during combat

conditions. This GTWM (smart shirt) provides an extremely versatile framework

for the incorporation of sensing, monitoring and information processing devices.

The principal advantage of smart shirt is that it provides for the first time a very

systematic way of monitoring the vital signs of humans in an unobtrusive

manner.

2.2.1.REQUIREMENTS OF SMART SHIRT

Casualties are associated with combat and sometimes are inevitable.

Since medical resources are limited in a combat scenario, there is critical need to

make optimum use of the available resources to minimize the loss of human life,

which has value that is priceless. In a significant departure from the past, the loss

of even a single soldier in a war can alter the nations engagement strategy

making it all the important to save lives.[2]



Similarly on the civilian side, the population is aging and the cost of the

health care delivery is expected to increase at a rate faster than it is today. With

the decreasing number of doctors in rural areas, the doctor/patient ratio is in

certain instances reaching unacceptable levels for ensuring a basic sense of

security when they leave the hospital because they feel “cutoff” from the

continuous watch and care they received in the hospital. This degree of

uncertainty can greatly influence their postoperative recovery. Therefore there is

a need to continuously monitor such patients and give them the added peace of

mind so that the positive psychological impact will speedup the recovery

process.

Mentally ill patients need to be monitored on a regular basis to gain a

better understanding of the relationship between their vital signs and their

behavioral patterns so that their treatments can be suitably modified. Such

medical monitoring of individuals is critical for the successful practice of

telemedicine that is becoming economically viable in the context of

advancements in computing and telecommunication, likewise continuous

monitoring of astronauts in space, of athletes during practice sessions and in

competition, of law enforcement personnel and combat soldiers in the line of

duty are all extremely important.

2.2.2 ARCHITECTURE

The GTWM was woven into a single –piece garment (an undershirt) on a

weaving machine to fit a 38-40” chest. The plastic optical fiber (POF) is spirally

integrated into the structure during the fabric production process without any

discontinuities at the armhole or the segms using a novel modification in the

weaving process.



fig.4.requirements of smartshirts



An interconnection technology was developed to transmit information

from (and to) sensors mounted at any location on the body thus creating a

flexible “bus” structure. T-connectors –similar to “button clips” used in clothing

are attached to the fibers that serve as a data bus to carry the information from

the sensors (eg: ECG sensors) on the body.

The sensors will plug into these connectors and at the other end similar T-

connector will be used to transmit their information for monitoring equipment or

DARPS (Defense Advanced Research Projects Agency) personnel status

monitor .By making the sensors detachable from the garments, the versatility

I\of the Georgia Tech Smart Shirt has been significantly enhanced. Since shapes

and sizes of humans will be different, sensors can be positioned on the right

locations for all users and without any constraints being imposed by the smart

shirt can be truly “customized”. Moreover the smart shirt can be laundered

without any damage to the sensors themselves.

The interconnection technology has been used to integrate sensors for

monitoring the following vital signs: temperature, heart rate and respiration

rate .In addition a microphone has been attached to transmit the weavers voice

data to monitoring locations. Other sensors can be easily integrated into the

structure. The flexible data bus integrated into the stricture transmits the

information from the suite of the sensors to the multifunction processor known

as the Smart shirt controller. This controller in turn processes the signals and

transmit them wirelessly to desired locations (eg: doctor’s office, hospital,

battlefield). The bus also serves to transmit information to the sensors (and

hence the weaver) from the external sources, thus making the smart shirt a

valuable information infrastructure.



fig.5.Architecture of smartshirt

A combat soldier sensor to his body, pulls the smart shirt on, and attaches

the sensors to the smart shirt. The smart shirt functions like a mo0therboard,

with plastic optical fibers and other special fibers woven throughout the actual

fabric of the shirt. To pinpoint the exact location of a bullet penetration, a

“signal” is sent from one end of the plastic optical fiber to a receiver at the other

end. The emitter and the receiver are connected to a Personal Status Monitor

(psm) worn at the hip level by the soldier. If the light from the emitter does not

reach the receiver inside the PSM, it signifies that the smart shirt has been

penetrated (i.e.; the soldier has been shot). The signal bounces back to the PSM

forum the point of penetration, helping the medical personnel pinpoint the exact

location the solider wounds.[6]

The soldiers vital signs –heart rate, temperature, respiration rate etc. are

monitored in two ways: through the sensors integrated into the T-shirt: and

through the sensors on the soldier’s body, both of which are connected to the

PSM. Information on the soldiers wound and the condition is immediately

transmitted electronically from the PSM to a medical triage unit somewhere near



the battlefield. The triage unit them dispatches the approximate medical

personnel to the scene .The Georgia tech smart shirt can help a physician

determine the extent of a soldiers injuries based on the strength of his heart beat

and respiratory rate. This information is vital for accessing who needs assistance

first during the so-called “Golden Hour” in which there are numerous casualties.



2.2.3. APPLICATIONS OF SMART SHIRT

• Combat casualty care.

• Medical monitoring.

• Sports/ Performance monitoring.

• Space experiments.

• Mission critical/ hazardous application.

• Fire- fighting.

• Wearable mobile information infrastructure.

The vital signs information gathered by the various sensors on the body

travels through the smart shirt controller for processing, from these, the

computed vital signals are wirelessly transmitted using the “communication

information infrastructure” in place in that application (e.g.: the firefighters,

communication systems, battlefield communication infrastructure, the hospital

network) to the monitoring station. There, the back-end Data display and

Management system – with a built –in knowledge –based decision support

system- in reverse these vital signs ask in real-time and provide the right

response to the situation.

Table 1 summarizes the broad range of application of the smart shirt

technology. The table also shows the application type and the target population

that can utilize the technology.





fig.5.Applications of smartshirt

2.2.4. IMPACT OF THE SMART SHIRT

The smart shirt will have significant impact on the practice of medium

since it fulfills the critical need for a technology that can enhance the quality of

life while reducing the health care cost across the continuum of life that is from

newborns to senior citizens, and across the continuum of medical care that is

from hospitals and everywhere in between.



The smart shirt can contribute to reduction in health care cost while

enhancing the quality of life. For instance, patients could wear the smart shirt at

home and be monitored by a monitoring station; thereby avoiding hospital stay

cost and reducing the overall cost of healthcare. At also same home, a home

setting can contribute to faster recovery. For example, if the patient recovering at

home from heart surgery is wearing the smart shirt, the ECG can be transmitted

wirelessly (through mobile phone, internet etc) to the hospital on a regular basis.

This monitoring will help the patient feel more “secure” and will facilitate the

recuperation while simultaneously reducing the cost time associated with

recovery. Moreover, in the event of an emergency, the doctor can be notified

instantaneously. Using the online medical records (available over the web) the

physician can administrate the right investment at the right time at the right cost

and indeed save a life, thereby realizing the full potential of the smart shirt

technology.

Further more, persons who have known disorders can wear the smart shirt

and be under constant monitoring of the physical conditions by medical

personnel. Yet another potential impact of the smart shirt technology is the

eventual disappearance of geographical/physical boundaries as barriers for

individual seeking the best in healthcare worldwide.

The smart shirt technology has the means to provide unobstructed

monitoring for individuals and can thereby play a critical role disease

management for the large numbers of individuals at risk for high blood pressure,

heart disease, diabetes, chronic bronchitis, and depression by enabling early

systematic intervention.



2.2.5.ADVANTAGES OF THE SMART SHIRT

• Continuous monitoring

• Right Treatment at the right time at the right cost

• Easy to wear and takeoff.

• Reducing the health care cost

DISADVANTAGES OF THE SMART SHIRT

• Initial cost is high

• Battery life is less



3.FUTURE TRENDS

By providing the “platform” for a suite of sensors that can be utilized to

monitor an individual unobtrusively. Smart Shirt technology opens up existing

opportunities to develop “adaptive and responsive” systems that can “think” and

“act” based on the users condition, stimuli and environment. Thus, the rich vital

signs delta steam from the smart shirt can be used to design and experiment

“real-time” feedback mechanism (as part of the smart shirt system) to embrace

the quality of care for this individual by providing appropriate and timely

medical inspections.

Certain individuals are susceptible to anaphylaxis reaction (an allergic

reaction) when stung by a bee or spider and need a shot of epinephrine

(adrenaline) immediately to prevent above illness or even fatalities. By applying

advancement in MEMS (Micro-Electromechanical Systems) technology, a

feedback system including a dry delivery system-can be integrated into the smart

shirt. Of course mechanism to guard against inadvertent administration of dry

can be built as a part of the control system.

Likewise, the Smart shirt’s delta acquisition capabilities can be used to

detect the condition when an individual is lapsing into a diabetic shock and this

integrated feedback mechanism can provide the appropriate response to prevent

a fatality. Thus, the smart shirt represents yet another significant milestone in the

endeavor to save and enhance the quality of human life through the use of

advanced technologies.



4. CONCLUSION

The ring sensor and smart shirt are an effective and comfortable, and

mobile information infrastructure that can be made to the individual’s

requirements to take advantage of the advancements in telemedicine and

information processing. Just as special-purpose chips and processors can be

plugged into a computer motherboard to obtain the required information

processing capability, the smart shirt is an information infrastructure into which

the wearer can “plug in” the desired sensors and devices, thereby creating a

system for monitoring vital signs in an efficient and cost effective manner with

the “universal“ interface of clothing.

Advanced technologies such as the smart shirt have at partial to

dramatically alter its landscape of healthcare delivery and at practice of medicine

as we know them today. By enhancing the quality of life, minimizing “medical”

errors, and reducing healthcare costs, the patient-control wearable information

infrastructure can play a vital role in realizing the future healthcare system. Just

as the spreadsheet pioneered the field of information processing that brought

“computing to the masses”. It is anticipated that the smart shirt will bring

personalized and affordable healthcare monitoring to the population at large,

thus leading to the realization of “Affordable Healthcare, Any place, Anytime,

Anyone”.



5. REFERENCES

1. H.Harry Asada, “mobile monitoring with wearable ppg sensors”,IEEE

engineering in medicine and biology magazine,vol 22, pp- 28-39 may/june 2003.

2. Park and Jayaraman,”enhancing the quality of life through wearable

technology”, IEEE engineering in medicine and biology magazine,vol 22, pp-

41-48 may/june 2003.

3. Handbook of biomedical instrumentation ,Khandpur ,pp-138,233,238

4. R.Neuman,”biomedical sensors”,handbook of biomedical

instrumentation,pp-725-755

5. http://www.smartshirt.gatech.edu

6. http://www.wearables.gatech.edu


http://www.wearables.gatech.edu/

http://www.smartshirt.gatech.edu/


ABSTRACT

Recent advancements in miniature devices have fostered a dramatic

growth of interest of wearable technology. Wearable Bio-Sensors (WBS) will

permit continuous cardiovascular (CV) monitoring in a number of novel

settings. WBS could play an important role in the wireless surveillance of

people during hazardous operations (military, firefighting, etc) or such sensors

could be dispensed during a mass civilian casualty occurrence. They typically

rely on wireless, miniature sensors enclosed in ring or a shirt. They take

advantage of handheld units to temporarily store physiological data and then

periodically upload that data to a database server via wireless LAN or a cradle

that allow Internet connection and used for clinical diagnosis.



CONTENTS

1. INTRODUCTION

2. DEVELOPMENT OF WEARABLE BIOSENSOR

2.1. RING SENSOR

2.1.1 BASIC PRICIPLE

2.1.2 WORKING

2.1.3 BLOCK DIAGRAM

2.1.4 APPLICATIONS

2.1.5 ADVANTAGES AND DISADVANTAGES

2.2. SMART SHIRT (WEARABLE MOTHERBOARD)

2.2.1 REQUIREMENTS

2.2.2 ARCHITECTURE

2.2.3 APPLICATIONS

2.2.4. IMPACTS

2.2.5. ADVANTAGES AND DISADVANTAGES

3. FUTURE TRENDS

4. CONCLUSION

5. REFERENCES



ACKNOWLEDGEMENT

I extend my sincere gratitude towards Prof. P.Sukumaran Head of

Department for giving us his invaluable knowledge and wonderful technical

guidance

I express my thanks to Mr. Muhammed Kutty our group tutor and also

to our staff advisor Ms. Biji Paul and Mr. Santhosh Kumar for their kind

co-operation and guidance for preparing and presenting this seminar.

I also thank all the other faculty members of AEI department and my

friends for their help and support.


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DEVELOPMENT OF WEARABLE BIOSENSOR - Latest Seminar · PDF fileSeminar Report ’03 Wearable Bio-Sensors 2.DEVELOPMENT OF WEARABLE BIOSENSOR 2.1.RING SENSOR It is a pulse oximetry sensor